kernel panic-not syncing: VFS: unable to mount root fs on unknown block(0,0)

OK, so I have fallen down a rabbit hole without much of a back up plan so I am hoping someone will be able to guide me through recovering my Linux install. I have limited knowledge of linux systems and Ubuntu so it’s probably what has got me in the mess in the first place so will try and best explain what has happened so far.

So I needed to clear space in /boot as Webmin was reported low storage.

uname -a reported 4.4.0-137-generic as my current kernal.

I ran a similar command as this, making sure the current kernel wasn’t listed:

sudo dpkg --list 'linux-image*'|awk '{ if ($1=="ii") print $2}'|grep -v `uname -r`

This as now left me with 4.4.0-137-generic, 4.4.0-138-generic and 4.4.0-139-generic, however none of them boot as I get the following error:

kernel panic-not syncing: VFS: unable to mount root fs on unknown
block(0,0)

I have tried the chroot options below:

sudo fdisk -l
sudo mount /dev/sdax /mnt
sudo mount --bind /dev /mnt/dev
sudo mount --bind /dev/pts /mnt/dev/pts
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt

However after I mount sda1 I can’t go any further, mnt shows the /boot folder and I can mount the dev folder as they don’t exist in /mnt.

I have tried the following when I was able to boot in to 4.4.0-137-generic and a few other options:

update-initramfs -u -k 4.4.0-137-generic

Which hasn’t resolved the issue, I used to be able to see the GRUB menu for recovery options however that is no longer showing, I am currently getting in to tty which is showing 4.4.0-139-generic when running the uname -a command.

This is my first post so excuse incorrect formatting and the lack of information for steps taken, might have been a little gun ho with this all. Let me know if I can amend anything for future reference.

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So to follow up, found my root partition is under /dev/mapper/Server--vg-root and I was able to mount all the folders for chroot however the recovery CD was 32-bit and need 64 which is my next step.

However the folder /dev/mapper/Server--vg-root/boot is empty, though /dev/boot is not. Do I need to mount it using the following command or am I supposed to be repairing /dev/mapper/Server--vg-root/boot to contain items?

sudo mount --bind /dev/sda1 /mnt/boot

Or how do I check which folder Grub is using to confirm which one needs repairing?